DESCRIPTION: (Verbatim from the Applicant's Abstract): This proposal describes a new family of small synthetic amphiphiles that are intended to promote three-dimensional crystallization of intrinsic membrane proteins. Membrane protein crystallization is necessary for high-resolution structural analysis, which, in turn, is essential for understanding protein function. Only about two dozen membrane protein crystal structures have been solved to date, and the rate-limiting step in structural analysis appears to be crystallization. Thus, if we are able to increase the number of membrane proteins that can be structurally analyzed, this research will have a profound effect on structural biology. Membrane proteins are solubilized, and therefore crystallized, as protein-detergent complexes. Conventional detergents are very flexible molecules; our hypothesis is that this flexibility disfavors growth of crystals containing detergents. We seek to replace conventional detergents with more rigid molecules that we call "tripod amphiphiles." Tripod amphiphiles contain a tetrasubstituted carbon atom that bears three hydrophobic appendages and one hydrophilic appendage. These amphilphiles are synthesized by an efficient and general route, which makes it easy to explore the effects of incremental changes in amphiphile structure. Our efforts are focused on crystallizing three intrinsic membrane proteins, bacteriorhodopson and sensory rhodopsin-I from Halobacterium salinarium, and bovine rhodopsin, all of which are readily available to us.